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Interest-only mortgage calculator

Work out your repayments before and after the interest-only period

Page reading time: 2 minutes

This calculator helps you work out:


  • This is a model, not a prediction. Amounts and repayment periods are estimates only, actual amounts may be higher or lower.
  • Results are based on information you have provided and do not take your personal circumstances into account.
  • This calculator applies to loans which have an interest-only period, then for the remaining period of the loan, both principal (amount borrowed) and interest are repaid.
  • Initial inputs will be displayed on the left hand side of the calculator.
  • The graph displays the periodic repayments for an interest-only loan and the repayments for a comparable principal and interest loan with the same amount borrowed, interest rate, repayment frequency and fees as the interest-only loan.
  • This calculator is not intended to be your sole source of information when making a financial decision. You may wish to consider getting advice from a licensed finance professional.
  • Using this calculator does not guarantee you will be eligible for a loan. You will need to satisfy your lender's lending criteria.


  • Interest rates do not change for the life of the loan.
  • Interest is calculated by compounding on the same frequency as the repayment selected, i.e. weekly, fortnightly, monthly quarterly or annually.
  • It does not take into account up-front fees, such as loan establishment fees.
  • It does not consider your ability to make the repayments shown. To help you consider the impact of interest rates changes, we suggest exploring the impact of a 2% interest rate rise. Interest rates could rise in future by more than 2%.
  • Affordable repayments cannot be less than the fees entered.